Idle air control

ABSTRACT

Idle airflow is bypassed around the closed throttle in an internal combustion engine induction passage and controlled by poppet and slide valve embodiments of an idle air control valve to regulate engine idle speed. The valves are positioned by a power element which is electrically heated to a predetermined temperature during the engine warmup period.

United States Patent Eckert et all.

[54] IDLE AIR CQNTROL [56} References Cited [72] Inventors: Clarence .1. Eckert; Benedetto C. Nardone, UNFTED STATES PATENTS both Of Rochester, 1,863,715 6/1932 Heitger ..123/l24 A 1,913,131 6/1933 Sisson ..123/124A [73] Asslgneez General Motors Corporation, Detroit, 2,519,607 8/1950 Steynor 123/124 B 3,030,027 4/1962 Reppert ..123/124 A [22] Filed: May 25, 1970 Primary ExaminerTim R. Miles l l PP N04 411141 Attorney-J. L. Carpenter and C. K. Veenrstra [52] us. c1 ..26l/39 A, 261/41 13, 261/63, [57] ABSTRACT 123/124 B ldle airflow is bypassed around the closed throttle in an inter- 51 1111.0 ..1F02m 23/10 nal combustion engine induction p g and controlled y [58] Field ofSearch ..261/39A,41 1), 63; 122/124 B, P pp and Slide valve embodiments of an idle air control 122/124 A valve to regulate engine idle speed. The valves are positioned by a power element which is electrically heated to a predetermined temperature during the engine warmup period.

1 Claims, 6 Drawing Figures 5 9 1 55 I0 56 l 5 0 26 Z? 1 54 e I 50 O Patented Feb. 29, 1972 3,645,509

5 Sheets-Sheet l "Wilh- M Q /"4/ 11 x1e ATTORNEY Patented Feb. 29, 1972 3,645,509

3 Sheets-Sheet 2 INVENTORS Clarence 156W 5 dtrf ATTO RNEY Patented Feb. 29, Jim}? 3 Sheets-Sheet 5 INV/ UPS Clarence J 62:11am? fiene'deziv C Nardone ATTORNEY IDLE AIR CONTROL This invention relates to idle speed control of an internal combustion engine and is directed to a valve mechanism which controls the flow of idle air bypassed around the throttle to provide the higher idle speeds required during the period immediately after the engine is started.

This valve mechanism is operated by a heated, temperature responsive element to vary idle speed from the highest idle speeds required for cold operation to curb idle speed over a preselected period of time, dependent essentially only upon the initial temperature. In the embodiments shown herein, this is achieved by positioning the idle air control valve by a power element and by heating the power element with a material having a positive temperature coefficient such that, below a predetermined temperature, electrical current is passed therethrough for heating and such that, above the predetermined temperature, the resistance of the material reduces current flow to a rate which maintains the power element at the predetermined temperature.

The details as well as other objects and advantages of this invention are set forth below and shown in the drawings in which:

FIG. 1 is a top plan view of an induction passage throttle body and illustrates a poppet valve embodiment of the idle air control valve deposed adjacent the throttle bores;

FIG. 2 is a side elevation view of the throttle body, taken in section along line 2-2 of FIG. 1, illustrating the idle airflow passages and the poppet type idle air control valve together with a separate curb idle adjusting screw;

FIG. 3 is a schematic sectional view illustrating the point of discharge from the idle airflow passages into the induction passages, taken generally as indicated by line 3-3 of FIG. I;

FIG. 4 is a view of a poppet-type idle air control valve, similar in most respects to that of FIG. 2, enlarged to show the details of the power element construction;

FIG. 5 is a top plan view of a slide valve embodiment of the idle air control valve, taken in section as indicated generally by line 5-5 of FIG. 6, showing the details of construction of the power element and schematically illustrating the connections to the induction passage;

FIG. 6 is a side elevational view of the slide valve shown in FIG. 5, with the cover removed as indicated generally by line 6-6 of FIG. 5.

Referring first to FIGS. I4, a throttle body 10 is provided with induction passages 12 having throttles I4 rotatably disposed on a shaft 16. As shown in FIGS. 2 and 3, an idle air discharge passage l8 discharges into induction passages 12 below throttles 14 from an idle air cross passage 20.

A curb idle air passage 22 discharges from a well 24 formed in throttle body 10 to cross passage 20. The rate of airflow through curb idle air passage 22 is controlled by an adjusting screw 26 to thereby control engine curb idle speed. A poppettype fast idle control valve 28 is received in well 24 and controls airflow from well 24 to cross passage through a path parallel to curb idle air passage 22.

The poppet structure shown in FIG. 4 differs from that shown in FIG. 2 only in the details of certain parts. Therefore, while the FIG. 2 valve is identified as 28, the FIG. 4 valve will be identified as 28'; the parts of valve 28 will be similarly related to the pans of valve 28; and the description of one valve will suffice as the description of the other valve.

Idle air control valve 28 has a housing 30 including a threaded fitting 32 secured in throttle body 10 with a gasket 34 disposed therebetween. Housing 30 has an axially extending peripheral wall 36 with lateral openings 38 permitting airflow into housing 30 from well 24. Housing 30 further includes a transversely extending annular end wall 40 defining a valve seat 42 surrounding an opening 44 connected to cross passage 20.

A cupped receptacle 46 is disposed within housing 30 and has a conically shaped transversely extending portion 48 defining a valve element which cooperates with valve seat 42 to vary the effective area of opening 44 and thereby control fast idle airflow through opening 44 from within housing 36 to induction passage I2. Receptacle 46 is biased away from valve seat 42 by a spring 50.

As described in greater detail below, receptacle 46 includes a heating element 52 and receives a power element 54 having a plunger 56. A washer or clip 58 is secured to plunger 56 and provides a radially extending flange forming a stop for a spring seat member 60. A spring 62 biases spring seat 66, and thus clip 58 and plunger 56, away from a nylon cover member 64 which closes housing 30. Plunger 56 has a threaded portion 66 which extends through a central opening 67 in cover member 64 and cooperates with a nut 68 bearing against the upper surface 70 of cover 64 to adjust the initial position of plunger 56 and thus of power element 54 and receptacle 46 to thereby ad just valve element 48 relative to valve seat 42.

As shown in greater detail in FIG. 4, power element 54', in a manner similar to power element 54, has a cup 72' received within receptacle 46 and containing a mass of thermally expansible material 74. A seal 76' retained by a backing member 78' encloses material 74' within cup 72'. Plunger 56' is received by seal 76 and is displaceable axially out from cup 72' upon thermal expansion of material 74'. As plunger 56' is so displaced, clip or washer 5% is axially displaced from backing member 78'.

Heater 52, in a manner similar to heater 52, includes an aluminum cup 80' surrounding power element cup 72 and insulated therefrom by a Mylar sleeve 82'. A sintered barium titanate disc 84 is disposed in the bottom of cup 80' and, together with a copper disc 86, is secured. therein by a metal filled epoxy.

As shown in FIGS. 1 and 2, an electrical lead has a terminal cap 88 disposed over the tip 90 of plunger 56. In the FIG. 2 embodiment, a groove 92 in nut 68 retains terminal cap 88 against accidental displacement; in the FIG. 4 embodiment, a pair of spring members 94 engage notches in a terminal cap (not shown).

Cover member 64 is electrically nonconductive so that a path for current flow is defined from terminal cap 88 through plunger 56, washer or clip 58 and spring seat member 60, a light contact spring 96, backing member 78 and power element cup 72, discs 86 and 84 and cup 80 of receptacle 46, and spring 50 to grounded housing 30. As the engine is started and current passes through the heating disc 84, it converts the electrical energy to heat energy and heats the thermally expansible mass '74, thus displacing plunger 56 from power element cup 72. Spring 50 is weaker than spring 62, and valve element 48 approaches valve seat 42 to reduce idle air flow to the engine and thus reduce the engine idle speed. Disc 84 has a positive temperature coefficient such that when a predeter' mined temperature is reached, current flow therethrough is substantially reduced. Thus disc 84 will maintain power element 54 at the preselected temperature.

Should additional heating of power element 54 occur after valve element 48 is seated on valve seat 42, plunger 56 overcomes spring 62 and nut 68 is lifted away from end wall 7 0 of cover member 64. A skirt 98 on cover 64 insulates the upper portion of housing 30 to reduce the cooling effect of airflow passing around valve 28 to induction passages 12.

Referring now to FIGS. 5 and 6, a housing 100 is closed by a cover 1102 to define a chamber 104 having an inlet opening 106, for receiving airflow from a location in induction passage I2 above throttle I4, and an outlet opening 108 for discharging airflow to induction passage 12 below throttle I4. Outlet opening 1108 is disposed in a planar wall III] of housing I00, and a slide valve member II2 overlies opening 103. Slide valve 112 has a contoured port I14 which cooperates with outlet opening 1108 to vary the effective area thereof. A spring 1116 has a pair of arms H8 at each end which clip over slide valve M2 and a 37 U"-shaped projection I20 bearing against cover 1162 to bias slide valve I12 against wall lllll and prevent air leakage therebetween. Slide valve 112 :is biased to the right by a spring I22. A link, here indicated as an adjusting screw i124, extends from slide valve 1112 to a plunger H26 of a power element 122.

As in the poppet valve embodiment described above, power element 128 has a cup 130 containing a mass of thermally expansible material 132. A seal 134 held in place by a backing member 136 retains material 132 within cup 130. Power element 128 is received by an aluminum receptacle 138 having a Mylar insulating sleeve 140, a sintered barium titanate disc 142, and an aluminum cap 144. An electrical lead 146 extends through a grommet 148 in housing 100 to heating disc 142, and a path for electrical current is defined through heating disc 142, cap 144 and power element cup 130 to grounded housing 100. A spring 150, with an insulating washer 152, biases receptacle 138 against power element 128 to assure heating of power element 128 by heating disc 142. An insulating sleeve 154 surrounds receptacle 138, and an insulating shield 156, biased by a retainer spring 158 covers power element 128 to prevent cooling of the power element by air flow through housing 100.

In operation, as the engine is started electrical current is supplied through lead 146 and causes disc 142 to heat power element 128; plunger 126 is then displaced from power element cup 130 and moves slide valve 112 toward the left to reduce idle airflow to the engine and thus reduce engine idle speed. Disc 142 has a positive temperature coefficient such that when a predetermined temperature is reached, current flow therethrough is substantially reduced. Thus disc 142 will maintain power element 128 at the preselected temperature.

A curb idle adjusting screw 160 controls airflow through a curb idle air passage 162 parallel to chamber 104, bypassing throttle 14 to control engine curb idle speed.

In each of the foregoing embodiments, the characteristics of the power elements are such that the thermally expansible material begins to expand at about F. and provides about 0.4 inch travel of the plunger for the slide valve and about 0.15 inch travel of the plunger for the slide valve and about 0.15 inch travel of the plunger for the poppet valve between 0 and 200 F. Similarly, the characteristics of the heating disc are such that their resistance is about 14 ohms at 77 F., about 3 minutes are required to increase the temperature from about 0 to about 250 F., and the resistance changes to maintain a temperature of about 250 F.

It will be appreciated that, with the structure set forth herein, a high engine idle speed is provided immediately after the engine is started and over a period of about 3 minutes, while the engine is warming up, the idle speed is gradually reduced to curb idle speed.

We claim:

1. In an internal combustion engine having an induction passage for airflow to the engine and a throttle in said induction passage movable between open and closed positions for controlling airflow therethrough: means for controlling idle airflow into said induction passage downstream of said throttle and thus for controlling the idle speed of said engine when said throttle is in closed position, said means comprising a hollow housing including an axially extending peripheral wall having a lateral opening to permit airflow into said housing, said housing also including a transversely extending annular end wall defining an opening connected with said induction passage downstream of said throttle, said end wall further defining a valve seat surrounding said opening; a cupped receptacle disposed within said housing and including a transversely extending base portion and an axially extending peripheral wall portion, said base portion including. a valve element cooperating with said valve seat to vary the effective area of said end wall opening and thereby control airflow through said end wall opening from said housing to said induction passage; first spring means extending between said housing and said receptacle and biasing said valve element away from said valve seat; a power element including a cup received by said receptacle, a mass of thermally expansible material disposed in said cup, a seal enclosing said material in said cup, a plunger received by said seal and displaceable axially from said cup upon thermal expansion of said material, said plunger having a radially extending flange, and second spring means interconnecting said plunger flange and said cup 11'] al relative positions thereof; a cover closing said housing and having an opening extending axially therethrough receiving said plunger; third spring means extending between said cover and said plunger flange and biasing said plunger toward said cup; and means for adjusting the initial position of said plunger relative to said cover; wherein said receptacle includes heating means for converting the electrical energy of current flow into heat energy, said heating means being in electrical and thermal Contact with said power element cup whereby current flow through said heating means will result in-thermal expansion of said thermally expansible material; wherein said cover is electrically insulative and said plunger, said second spring means, said cup, said receptacle, said first spring means, and said housing are electrically conductive to define a path for current flow through said heating means; and wherein said first spring means is weaker than said second spring means whereby said cup and said receptacle move toward said end wall of said housing against the bias of said first spring upon initial expansion of said thermally expansible material and whereby said plunger overrides said third spring and moves away from said end wall of said housing upon continued expansion of said thermally expansible material following seating of said valve element on said valve seat. 

1. In an internal combustion engine having an induction passage for airflow to the engine and a throttle in said induction passage movable between open and closed positions for controlling airflow therethrough: means for controlling idle airflow into said induction passage downstream of said throttle and thus for controlling the idle speed of said engine when said throttle is in closed position, said means comprising a hollow housing including an axially extending peripheral wall having a lateral opening to permit airflow into said housing, said housing also including a transversely extending annular end wall defining an opening connected with said induction passage downstream of said throttle, said end wall further defining a valve seat surrounding said opening; a cupped receptacle disposed within said housing and including a transversely extending base portion and an axially extending peripheral wall portion, said base portion including a valve element cooperating with said valve seat to vary the effective area of said end wall opening and thereby control airflow through said end wall opening from said housing to said induction passage; first spring means extending between said housing and said receptacle and biasing said valve element away from said valve seat; a power element including a cup received by said receptacle, a mass of thermally expansible material disposed in said cup, a seal enclosing said material in said cup, a plunger received by said seal and displaceable axially from said cup upon thermal expansion of said material, said plunger having a radially extending flange, and second spring means interconnecting said plunger flange and said cup in all relative positions thereof; a cover closing said housing and having an opening extending axially therethrough receiving said plunger; third spring means extending between said cover and said plunger flange and biasing said plunger toward said cup; and means for adjusting the initial position of said plunger relative to said cover; wherein said receptacle includes heating means for converting the electrical energy of current flow into heat energy, said heating means being in electrical and thermal contact with said power element cup whereby current flow through said heating means will result in thermal expansion of said thermally expansible material; wherein said cover is electrically insulative and said plunger, said second spring means, said cup, said receptacle, said first spring means, and said housing are electrically conductive to define a path for current flow through said heating means; and wherein said first spring means is weaker than said second spring means whereby said cup and said receptacle move toward said end wall of said housing against the bias of said first spring upon initial expansion of said thermally expansible material and whereby said plunger overrides said third spring and moves away from said end wall of said housing upon continued expansion of said thermally expansible material following seating of said valve element on said valve seat. 